Polysiloxane-containing rubber composition

Abstract

A rubber composition having improved properties containing a starting rubber (e.g., diene rubber) and a polysiloxane having the following alkoxysilyl group (I) and/or acyloxysilyl group (II) and having an average degree of polymerization of 3 to 10,000:wherein, R1 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 18 carbon atoms or an organic group containing an ether bond and R2 is hydrogen or a hydrocarbon group having 1 to 21 carbon atoms.

What is claimed is:  
     
       1. A rubber composition comprising: (i) 100 parts by weight of at least one rubber selected from the group consisting of natural rubber, polyisoprene rubber, styrenebutadiene copolymer rubber, polybutadiene rubber, acrylonitrilebutadiene copolymer rubber, butyl rubber, a diene rubber and ethylene-propylene copolymer rubber; (ii) from 5 to 100 parts by weight of a polysiloxane surface-treated silica comprising (a) 100 parts by weight of silica surface treated by (b) 0.1-50 parts by weight of a polysiloxane having a repeating unit of the formula (III):                    
       wherein R 3  independently represents a methyl group, an ethyl group, or a phenyl group, R 4  independently represents hydrogen or an organic group, R 5  independently represents an alkyl group or acyl group, m is 0 or an integer of 1 or more, and n is an integer of 1 or more; and (iii) a sulfur-containing silane coupling agent in an amount of from 0.5-40% by weight based on the total amount of the silica. 
     
     
       2. The rubber composition of  claim 1 , wherein said sulfur-containing silane coupling agent is selected from the group consisting of bis-[3-(triethoxysilica)-propyl]tetrasulfide, bis-[3-(triethoxysilyl)propyl]-tetrasulfide, 3-trimethoxysilypropyl-N,N-dimethylthiocarbamoyltetrasulfide, trimethoxysilyl-mercaptobenz-thiazoletetrasulfide, triethoxysilylpropyl-methacrylatemonosulfide and dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl-tetrasulfide.